WASHINGTON: US President Donald Trump has ordered the deployment of two nuclear submarines, in an extraordinary escalation of what had been an online war of words with a Russian official over Ukraine and tariffs.

The US president and Dmitry Medvedev, the deputy chairman of Russia`s security council, have been sparring on social media for days. But Trump`s post on his Truth Social platform abruptly took that spat into the very real and rarely publicised sphere of nuclear forces.

`Based on the highly provocative statements,` Trump said he had `ordered twoNuclear Submarines to be positioned in the appropriate regions, just in case these foolish and inflammatory statements are more than just that.

`Words are very important, and can often lead to unintended consequences, I hope this will not be one of those instances,` the 79-year-old Republican posted.

The nuclear sabre rattling came against the backdrop of a deadline set by Trump for the end of next week for Russia to take steps to ending the Ukraine war or face unspecified new sanctions.

Despite the pressure from Washington, Russia`s onslaught against its pro-Westernneighbor continues to unfold at full-bore.

Trump did not say in his post whether he meant nuclear-powered or nuclear-armed submarines. He also did not elaborate on the deployment locations, which are kept secret by the US military.

The United States and Russia control the vast majority of the world`s nuclear weaponry, and Washington keeps nuclear-armed submarines on permanent patrol as part of its so-called nuclear triad of land, sea and air-launched weapons.

Trump also did not refer specifically to what Medvedev had said to prompt his order.-AFP